What is a rising main?

A rising main is a pressurised pipe that carries pumped effluent or water uphill from a pumping station to a gravity sewer or discharge point. Unlike gravity drains, rising mains flow under pressure and can go uphill. They are typically 50-110mm MDPE or ductile iron pipe.

What velocity should a rising main have?

The ideal velocity in a rising main is 0.7-1.2 m/s for foul sewage. Below 0.7 m/s, solids settle and cause blockages. Above 1.5 m/s, friction losses become excessive and water hammer risk increases on pump stop. Select a pipe diameter that gives velocity within this range.

What is a non-return valve (NRV)?

A non-return valve (also called a check valve) is always required on a rising main to prevent backflow when the pump stops. Without an NRV, the sewage in the rising main would flow back into the pump chamber. It is installed on the rising main immediately after the pump discharge.

How do I calculate friction head loss?

Friction head loss depends on pipe diameter, flow rate, pipe material and length. It is typically calculated using the Hazen-Williams or Darcy-Weisbach equation. Bends, valves and fittings add equivalent length — typically 1.5m per bend. The result is added to static head for total pump head.

What pipe material should I use?

MDPE (Medium Density Polyethylene) is the standard choice for domestic and small commercial rising mains. It is flexible, corrosion-resistant and easy to join. Ductile iron is used for larger installations or where the pipe passes under roads. uPVC can be used but is less flexible.

TradeCalculator

Rising Main Calculator — Pipe Size, Friction Head & Pump Duty

Calculate rising main pipe diameter from flow rate, friction head loss, total pump head and pipe velocity for sewage or water pumping stations.

Flow Rate

Design pump flow rate

Static Head

Vertical lift from pump to discharge

Pipe Length

Total rising main length

Pipe Diameter

Pipe Material

Price Per Metre (optional)

Pipe material cost per metre

How We Calculate This

This calculator sizes a rising main pipe and calculates the total pump head required.

The formulae

Velocity = Flow Rate / Pipe Area

Friction Head = (Loss per 100m × Equivalent Length) / 100

Total Head = Static Head + Friction Head

Pump Power = (Flow × TDH × 9810) / (Efficiency × 1000)

Target velocities

Minimum: 0.7 m/s (self-cleansing)
Ideal: 0.7-1.2 m/s
Maximum: 1.5 m/s (water hammer risk)

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.